1. Field of the Invention
This invention relates to data processing systems and more particularly to an apparatus and method for automatically reconfiguring the local-memory/processor configuration and reinitiating a bootload sequence in the event of a failure in the start phase of the input/output processor (IOP) bootload.
2. Description of the Prior Art
A "bootstrap loader" is an elementary computer program generally of very short length (many times less than 20 instructions), which initiates the loading of either the operating system programs or any other desired programs into core or transistor storage for execution. In an error-free environment, the "bootstrap loader" is placed in the main random access memory or local random access memory only once. However, the area occupied by the bootstrap loader program is generally shared with other programs such as compilers, assembly language programs, etc. and sometimes inevitably gets written over by the loaded program. In order to obviate this difficulty and avoid the necessity of reloading such programs as the operating system from the disk memory, etc. many computer systems have provided a hardware or firmware bootloader apparatus for automatically initiating the loading of any desired program. Whereas this hardware or firmware type of bootloader apparatus obviates many of the difficulties previously encountered with a software program, it does not solve the problem where the bootload apparatus encounters trouble in the system such as a faulty memory or other faults wherein the automatic bootload is unable to load the desired program into a selected random access memory, or is unable to complete the bootload for some other undetermined reason. In such cases, prior art devices require operator intervention to reconfigure the system and reinitiate the bootload. This technique can be time-consuming, particularly where more than one fault is located in reconfiguring the system.
What is needed, therefore, is automatic reconfiguration hardware to automatically alter the local-memory-processor configuration and reinitiate the bootload sequence in the event of a failure in the start phase of the local memory/IOP bootload. More particularly, this automatic reconfiguration hardware should be capable of reconfiguring the system sequentially and automatically to produce at least (n) configurations without interruption when the preceding (n-1) configurations have been found faulty.